Many modern buildings are much taller and heavier than the buildings before them. The foundation piles deeply fixed into the ground or rock are widely adopted as the basis for supporting the buildings and maintain the stability of the same. The temperature variation of the soil around the foundation pile that is deeply fixed into the ground is much more stable as compared with the changing atmosphere temperatures where the building is located. Although the temperature of the soil changes along with different latitudes and seasons, it does not change drastically like the atmospheric temperature which will obviously change along with latitudes, climate, weather and even different times of the day. Therefore, based on the principle of heat exchange, appropriately utilizing the foundation pile to absorb thermal energy from underground for use in a building or a house improves energy efficiency and achieves the goal of green building.
In addition, many home appliances, such as a microwave oven, electric oven, refrigerator, electric cooker, induction cooker, steamer, air-conditioner and heating stove, are needed to satisfy the requirements of the modern lifestyle of a family. Normally, those home appliances will generate waste heat during operation and release thermal energy directly to the air without being properly recycled for use, and this is not environmentally friendly.
Therefore, if we can recycle the underground thermal energy or waste heat of the home appliances as mentioned above, it can be expected that a building or living environment with better energy efficiency can be achieved.